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// ----------------------------------------------------------------------------

// Main module providing the JTAG interface: definition

// Copyright (C) 2009  Embecosm Limited <info@embecosm.com>

// Contributor Jeremy Bennett <jeremy.bennett@embecosm.com>

// This file is part of the Embecosm cycle accurate SystemC JTAG library.

// This program is free software: you can redistribute it and/or modify it

// under the terms of the GNU Lesser General Public License as published by

// the Free Software Foundation, either version 3 of the License, or (at your

// option) any later version.

// This program is distributed in the hope that it will be useful, but WITHOUT

// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public

// License for more details.

// You should have received a copy of the GNU Lesser General Public License

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

// The C/C++ parts of this program are commented throughout in a fashion

// suitable for processing with Doxygen.

// ----------------------------------------------------------------------------

// $Id$

#ifndef JTAG_SC__H

#define JTAG_SC__H

#include "systemc"

#include "TapAction.h"

//! Default size of the FIFO queuing TAP actions

#define DEFAULT_TAP_FIFO_SIZE  256

//! The main JTAG interface module

//! This provides a pin interface on one side (to drive JTAG ports on a chip)

//! and a FIFO on the other, allowing the user to queue JTAG actions.

//! The pin interface is:

//! - sysReset (input)  The system reset. When this is asserted, the interface

//!                     will do nothing except drive TRST low.

//! - tck (input)       The JTAG clock (supplied externally)

//! - tdi (output)      Drives the TDI pin

//! - tdo (input)       Receives the TDO pin

//! - tms (output)      Drives the TMS pin

//! - trst (output)     Drives the TRST pin

//! @note The JTAG pins are reversed, because this module is @b driving the

//!       pins.

//! The FIFO allows the user to queue actions, which are of abstract type

//! TapAction::. This is subclassed to provide specific actions for reset

//! (TapActionReset::), DR-scan (TapActionDRScan::) and IR-scan

//! (TapActionIRScan::).

//! The size of the FIFO can optionally be specified in the constructor.

//! The class provides a method, sensitive to the clock, which reads actions

//! from the FIFO and processes them, issuing the requisite sequence of

//! changes of the JTAG pins until the action is complete. It then notifies

//! the action owner of completion, through an sc_event, which is part of the

//! ::TapAction class.

//! 

class JtagSC

  : public sc_core::sc_module

{

public:

  // The ports. Note that the naming of the low level JTAG ports is reversed,

  // because we are driving the inputs! */

  sc_core::sc_in<bool>   sysReset;      //!< The system reset (active high)

  sc_core::sc_in<bool>   tck;           //!< External JTAG TCK

  sc_core::sc_out<bool>  tdi;           //!< JTAG TDI pin

  sc_core::sc_in<bool>   tdo;           //!< JTAG TDO pin

  sc_core::sc_out<bool>  tms;           //!< JTAG TMS pin

  sc_core::sc_out<bool>  trst;          //!< JTAG TRST pin

  //! JTAG action queue

  sc_core::sc_fifo<TapAction *> *tapActionQueue;

  // Constructor and destructor

  JtagSC (sc_core::sc_module_name  name,

          int                      fifo_size = DEFAULT_TAP_FIFO_SIZE);

  ~JtagSC ();

protected:

  // Method to process the actions

  void  processActions();

private:

  //! The TAP state machine

  TapStateMachine *stateMachine;

  //! The next TAP action

  TapAction *currentTapAction;

};      // JtagSC ()

#endif  // JTAG_SC__H